February 18, 2008

Automotive Performance Envelopes

Every vehicle design is a compromise of many different demands. There are a number of major considerations that go into the design and development of each one. Here are eight off the top of my head: Weight, power, cost, fuel economy, safety, emissions, comfort, and reliability. Within these major considerations are many subgroups of further considerations or constraints.

Depending on the type of vehicle, there will be more emphasis on some of these characteristics than others. In the case of eight considerations, the envelope is an octagon. Each side of the octagon represents one characteristic or constraint.

The distance between the center of the octagon and a characteristic represents the state-of-the-art in automotive technology at the time the vehicle is developed, what is presently attainable. The design team decides how far along each of those spectrums they will emphasize or push. The closer to the edge of the octagon, the more emphasis there is. The area encompassed by the lines that connect the points on each of those spectrums is the performance envelope of the product. The larger the area, the more difficult the challenge.

Below are diagrams I sketched for a race car, a luxury car, and an economy car. As you can see, since everything is a compromise it is impossible to cover the entire area.

Over time as technology improves the spectrums get longer and the octagon (in this case) gets larger. This explains why today’s economy cars, whose designs don’t emphasize power, are more powerful than many sports cars of yesteryear. The performance envelopes have expanded greatly.

So where does this lead us? This is nothing new. But what should be developed is a standardized composite ranking across multiple characteristics by which many vehicles can be evaluated in an apples-to-apples comparison, and averages compiled. Combining that data with information from an automotive “dashboard” or snapshot (link), we can identify areas that most need improvement.

In other words, vehicles should be judged and measured in a consistent way against what is possible at that time, the state of vehicle technology should be monitored and tracked as it changes over time, and stakeholders (consumers, manufacturers, suppliers, regulators, etc) should have access to that information in order to make sound decisions. I think all the data is already out there but it’s currently piecemeal and needs to be neatly packaged in one location.